To monitor the prevalence of HIV risk behaviors, HIV infection, and the use of HIV prevention programs among populations at increased risk for HIV, the Los Angeles County Department of Public Health's (LACDPH) HIV Epidemiology Program proposes to implement an HIV behavioral surveillance system during 2008-2010. The system will involve alternating cross-sectional surveys among men who have sex with men (MSM), injecting drug users (IDU), and heterosexuals at risk for HIV infection (HET). The collected behavioral data will be used to inform local HIV prevention planning as well as to contribute to a national HIV behavioral surveillance database. The overall goal of this proposal is to obtain support to maintain an existing HIV behavioral surveillance system for monitoring of long-term trends in the prevalence of HIV risk behaviors among high-risk populations in Los Angeles County. Four specific aims have been identified to accomplish this goal: 1. Conduct annual behavioral surveys. The system will monitor the prevalence of HIV risk behaviors and access to and use of HIV prevention programs by administering standardized cross-sectional surveys to a minimum of 500 MSM, 500 IDU, and 500 heterosexuals at elevated risk of HIV infection in Los Angeles County. Time-space and respondent-driven sampling will be used to recruit participants for these surveys. 2. Offer HIV counseling and testing. Both rapid and standard HIV testing services will be offered to survey participants. HIV prevalence and HIV incidence estimates will be obtained for each risk population. 3. Collaborate with local partners. The HIV Epidemiology Program will engage local experts in qualitative research activities and will collaborate with local community agencies to develop local-use survey questions and implementation strategies. 4. Evaluate the NHBS system. Collaboration with the Centers for Disease Control and Prevention will enhance the program's ability to evaluate the local quality, efficiency, and value of national HIV behavioral surveillance data collection and implementation methods. [unreadable] [unreadable] [unreadable]